Email is not encrypted (so it's not private)!

Chances are, you use email. And chances are, you don't use encrypted email.

Gmail, Yahoo mail, etc. are all not encrypted!

Sending an email is like sending a letter in the mail. Between the time you put it in the mailbox to when your recipient finally receives it, your letter will be handled by many different people and go through different mail hubs and delivery vehicles. Anywhere along the path someone could potentially open your letter and read it. Similarly, email is sent through various hubs and handled by different servers, and anyone along the way could potentially read it. And say a delivery truck or storage facility (or computer system/hardware device in the case of email) is left open and unlocked, that makes your mail even more open. Just because you have to type a password to get to your mail, or because your email is delivered to your blackberry which only you access, does not mean it was safe during its journey.

Actually, sending an email is more like sending a postcard. When you send a letter in an envelope, the recipient is likely able to see if the envelope has been tampered with. However, with a postcard, anyone can read it along the way. You cannot tell if the message on your postcard has been kept private. Email is like that. If someone (or multiple people) reads your email, there's no way you can tell.

Email is also like a telephone call. Anyone who can listen on the line can find out what your email is about. Worse, the message in your email is likely "played" multiple times while it’s being delivered – between each node in which it is transferred.

Furthermore, copies of your email are probably made along the way to being delivered. If anyone can gain access to any of the systems holding a copy of your email, then it can be read. (BTW, your email administrator could easily read your mail.)

The moral of the story is when using [unencrypted] email, you should NOT send information considered private (such as account numbers, passwords, SSN, personal information, etc.) (Would you send cash through regular snail mail?)